The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in the present disclosure and are not admitted to be prior art by inclusion in this section.
A dual-connectivity network may be a network where a user equipment (UE) can connect with more than one cell site simultaneously. A cell site may be considered to be an evolved NodeB (eNB). When a UE connects to two (or more) eNBs, it may receive data from both eNBs at the same time. In embodiments, one of the eNBs may be considered a Master eNB (MeNB), and another of the eNBs may be considered a Secondary eNB (SeNB).
In some dual-connectivity networks, the MeNB may manage the transmission of PDCP packets to the UE. PDCP packets may also be referred to as PDCP service data units (SDUs). Specifically, the MeNB may transmit some PDCP packets to a UE, while the SeNB transmits others of the PDCP packets to the UE. However, in some cases the packets may be received by the UE out of order. For example, if a message includes ordered packets 1, 2, 3, and 4, the MeNB may transmit packets 1 and 3, while the SeNB may transmit packets 2 and 4. In some cases, the packets from the SeNB may arrive at the UE before the packets from the MeNB arrive at the UE. Additionally, in some cases the UE may disconnect from the SeNB during or immediately after the transmission of the packets, and the MeNB may not be able to identify whether the packets from the SeNB have been successfully received by the UE.